A lorry driver has pleaded guilty to killing a mother and three children in an eight-vehicle crash in Berkshire.
Tomasz Kroker, 30, collided with the victims' car on the A34 between Chieveley and West Ilsley on 10 August.
Reading Crown Court heard he was distracted by using a mobile phone.
Kroker, who admitted to four counts of causing death by dangerous driving and one count of causing serious injury by dangerous driving, will be sentenced on 31 October.
The court was told it would be shown video shot by a camera inside the lorry cab which shows Mr Kroker using the phone, and "the fast-approaching queue of vehicles."
Tracy Houghton, 45, from Dunstable, her two sons, Ethan, 13, and Joshua, 11, and her partner's daughter Aimee Goldsmith, 11, died in the crash.
A man was flown to hospital by air ambulance with serious injuries.
A further 11 people sustained minor injuries in the cash, which closed the northbound carriageway for about 12 hours.
Kroker, of Trajan Walk, Andover, was remanded in custody to appear for sentencing by a High Court judge sitting at Reading Crown Court.